I working on a FX3 board layout with USB3 functionality. The product relies on high speed USB3 data transfers. I was wonder if instead of using a USB A/C type connectors, if I can just use a 9 pin header (1.27mm pitch or 2.54mm pitch) and just solder a usb 3 cable to it

1) Will this work?

2) if yes, will there be any transfer speed limitations?

Can I use a FFC (Flat flexible cable) connector as another option? Are there any design requirements that I should keep in mind when using such a connector for USB3 communication rather than a typical USB 3 A/B/C connector?

The point is to have a USB cable attached to the board directly instead of a connector.